Depth Enabled Painting

From ZBrush Info

Paint Brushes

ZBrush offers many paint brushes found in other programs, plus some unique ones not found in other programs. Paint brushes are accessed via the tools popup, which can be found to the left of the canvas, or in the Tool Palette.

We won't discuss details of brushes here, but some of them will be explained in greater detail in other sections, and the Tool Palette gives brief descriptions of most of them. And of course, the way to really get to know a brush is to experiment with it.

Color Painting

Paint brushes can use color. (But color can be turned off, too.) Some brushes use two different colors, a foreground color and a background color. You'll see this in examples, and as you experiment on your own. You can look at the Color Palette reference for details of how to select colors. Do we need to say more?

Depth-Enabled Painting

This is one of the unique features of ZBrush, and an important one it is. When you paint on the canvas, you can affect not only the color but (optionally) the distance of pixels on the canvas from you, the viewer. In fact, in ZBrush, we call the smallest dots on the canvas pixols (not pixels), to indicate that in addition to all of the properties of normal pixels, pixols offer some unique features of their own.

The concept of depth-enabled painting is easier to show than to explain. In the figure below, the square on the left is some simple painting (a couple of strokes) I made on the canvas, using the default settings when ZBrush first starts. Then, in the middle of the figure, you can see exactly the same 'drawing', but with just the lighting changed. Because parts of the canvas have been raised, the direction of lights affect how things appear on the canvas. Yes, ZBrush provides lighting control, and it can be used to change the look of a painting without making a single brush stroke! Finally, on the right I pulled a little trick by converting the canvas to a polymesh, and then rotating that polymesh to show the depth of the original canvas. (There's no actual way of 'rotating' the canvas to see it from a side view.)

And by the way...painting with depth is really important in modeling, because it's how you add the finest level of detail to ZBrush models.

Clipping Planes

Once we allow painting with depth, we have the question–how 'deep' is the canvas, i.e. how near is the nearest point, and how far is the farthest point. Just like width and height, which must be finite for any image, so must depth.

In ZBrush, the range of depth of the canvas is fixed; you can't change it, unlike width or height. However, the range of depths is quite large (over 65,000 possible planes on which a pixol can be), so that's unlikely to be a problem.

Within all of those planes along the z-axis, three are of particular importance:

• The back plane is at the farthest distance at which a pixol can be drawn.
• The front plane is at the nearest distance at which a pixol may be drawn.
• The canvas plane is midway between the back and front planes. When you first start ZBrush, all the gray pixols you see on the canvas are at the distance of the canvas plane.